Apparatus for treating sheet material



y 1941- A. WALLACH 2,247,794

APPARATUS FOR TREATING SHEET MATERIAL Original Filed May 21, 1936 ANDREWALL/10H ATTORNEY Patented July 1, 1941 APPARATUS F MA R TREATING SHEETT ERIAL Andre Wallach, Atlanta, Ga., asslgnor to Sylvania IndustrialCorporation, Fredericksbllrg, Va a corporation of Virginia Originalapplication m 21, 1936. Serial No.

Divided and this application October 29, 1938, Serial No. 237,653

6 Claims.

The present invention relates to an apparatus for modifying the surfacecharacteristics of sheets of non-fibrous, relatively plastic materialsand the article produced thereby.

This application is a division of application Serial Number 81,054,filed May 21, 1936,- entitled Process and apparatus for treating sheetmaterial, which has matured into Patent No. 2,163,642, June 27, 1939.

Wrapping materials formed from non-fibrous, hydrophilic colloidalmaterials such as cellulose hydrate, cellulose ethers and esters,gelatin, casein and the like are characterized by a high surface gloss,a high degree of transparency, a smooth surface and a relativeexpansibility. Sheets of such materials tend to stick together whentightly rolled or stacked, especially when stored under pressure or inamosphere which varies with respect to temperature and humidity. Thetackiness of such plasticized sheet materials is dependent, among otherfactors, upon (1) the thickness of the sheets, (2) the nature and amountof the plasticizer and (3) the temperature and relative humidity of theambient atmosphere. Under the same atmospheric conditions, a thick sheetcan tolerate a larger percentage of plasticizer than a thin sheet. Thuswith sheets of cellulose hydrate varying in thickness of fromapproximately 0.0008 to 0.0016 of an inch, the glycerine content variescorrespondingly from about 11% to 19%.

The amount of plasticizer is varied with the seasons of the year.Cellulose hydrate sheets plasticized with 12% glycerine will exhibit noobjectionabletackiness on a moderate day in spring, while these sheetswill stick together on a humid day in summer and will be brittle on acold and dry day in winter or fall. As the temperature and relativehumidity increase, the tackiness of the sheets also increases.

The above-mentioned factors taken together with the smoothness of thesheet materials give rise to numerous difficulties in the use of thematerials. For example, when such material is cut into sheets and thesheets stacked, it frequently happens that the contiguous surfaces sticktogether to such an extent that it is difficult to separate theindividual sheets from the stack. Occasionally after prolonged storage,particularly when under pressure, the sheets stick together to such anextent that the stack may become substantially a unitary block of thematerial so that this action is commonly referred to in the trade asblocking. The sticking together of the sheets greatly decreases thespeed of manipulating such materials in manual wrapping and renders itsubstantially impossible to use such sheets in automatic machinesresulting in inconvenience, waste and expense.

It is a general object of the invention to prevent and/or decrease theblocking" of stacked sheets of plasticized non-fibrous materials whichhave blocked together, whereby to facilitate the ready separation ofindividual sheets from the stack.

It is a further object of the invention to provide an improved apparatusfor treating stacked sheets of non-fibrous, flexible materials to renderthe sheets insensitive, with regard to blocking" tendencies, to materialvariations in the amount of plasticizer, the relative humidity andtemperature of the ambient atmosphere and to conditions of storage.

It is a specific object of the invention to provide an apparatus fortreating stacked sheets of non-fibrous, flexible materials whereby todecrease the tendency of contiguous surfaces of the sheets to sticktogether and to decrease the tackiness of the surfaces thereof tofacilitate the use of the sheets in manual operations and in automaticmachinery.

It is another object of the invention to provide an apparatus forreconditioning stacked sheets of non-fibrous materials simultaneously toimprove their flexibility and to decrease the tendency of the sheets tostick together.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

It has now been found that stacked sheets of flexible non-fibrousmaterials may be rendered insensitive to variations in plasticizer,humidity, temperature and storage conditions generally by insertingbetween contiguous surfaces of the stacked sheets a small amount of acomminuted material. The edges of the sheets in a face of a stack,either before or after they have become stuck together, are subjectedto'a blast of a gas containing a comminuted material. If the sheets aretoo brittle, the stack may be subjected simultaneously or separately toa gas consisting ofor comprising a softening agent of the sheetmaterial. The apparatus of the invention comprises means to produce acurrent of a gas, such as air, means to disperse in the gas current acomminuted material and means to position a stack of sheets edgewise inthe gas current.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawing, in which:

Fig. l is a perspective view of one embodiment of the apparatus of theinvention;

Fig. 2 is an enlarged sectional view taken on line 2-2 of Fig. 1;

Fig. 3 is a detailed view in section with parts broken away of a sideelevation of a part of the apparatus of Fig. 1;

Fig. 4 is an enlarged sectional view with parts broken away of amodification of a part of the apparatus which is illustrated in Fig. 3;and

Fig. 5 is an embodiment of the stack-holding means of the apparatus ofFig. 1.

The apparatus is applicable for treating sheets of various non-fibrousmaterials, in particular,

colloidal materials swelling in water such, for

example, as cellulose hydrate, hydroxy-alkyl derivatives of cellulose,gelatin, casein and the like; as well as cellulose derivatives such, forexample, as cellulose acetate, cellulose nitrate, methyl cellulose andbenzyl cellulose; also rubber and synthetic resins such, for example, aspolymerized vinyl resins. glyptal resins and other nonfibrous sheetmaterials. It is to be understood that such sheet materials may or maynot con tain suitable plasticizers, fillers, and may or may not becoated and/or impregnated with waterproofing and moisture-proofingcompositions.

For the comminuted material there may be employed an inorganic ororganic solid, preferably one which is cheap, non-hygroscopic andrelatively soft so as not to scratch the surface of the sheet materials,the parts of automatic machinery in which the treated sheets may beused, or articles wrapped therein. Suitable comminuted materials areinorganic substances such as barium sulphate, zinc oxide, talc, fullersearth or organic substances such as flour, starch, dextrine, anthracene,alkali metal earth soaps, as well as comminuted material of likecharacter to the sheet material such as cellulose hydrate, cellulosederivatives, gelatine, casein and the like. While there is'a wide rangepermissible in the size of the particles of the comminuted material, ithas been foundpreferable, in order to obtain the correlated resultsherein described without interfering. with the generally accepted usesand properties of the sheet material, to employ material in the form ofa powder, the particles of which are not substantially greater thanthose which will pass through a 100 mesh screen and may have a sizecorresponding to 200 mesh or more. The comminuted material is applieduniformly over the surfaces of the sheet material in a very smallamount, preferably in an amount insuiiicient materially to detract fromthe normal appearance of the sheet material.

Referring to the drawing, Fig. 1 is a perspective view of one embodimentof an apparatus suitable for carrying out the process, in which acurrent of a gas may be supplied from a cylinder l having a valve I I,the gas flowing through a flexible conduit I2 having a pressure gauge l3to a manifold M and to a plurality of outlet nozzles |--|5. Thecomminuted material It contained in a vessel I1 is sucked into the pipe|2 adjacent the manifold M or directly into the manifold through a pipela, the bottom end of which dips into the comminuted material. The stackI! of sheets is supported upon a bed plate 20, preferably pivotallysupported upon a stand 2|. The bed plate is provided with a fixed backplate 22 and end plates 23 and 24. The end plate 23 is provided withconventional means to adjust its distance from the plate 24. A top plate25 is preferably supported on the end plate 24 by conventional means(not shown) for adjusting its height from the bed plate 20 whereby toaccommodate stacks of different heights therebetween. The end plate 24is provided with a plurality of slit-like openings 2626 corresponding inspacing and size tothe several nozzles |5--|5. The bed plate 24, beingpivotally mounted on the stand 2|, is provided with means such as a rod21 sliding in a sleeve 28 to vary the inclination thereof. To allow thebed plate to be pivotally moved the pipe |l should be formed of flexiblehosing or have a flexible section therein and the pipe l2 should beprovided with a suitable union or flexible section.

In the operation of the apparatus, a stack IQ of sheets is placed on thebed plate 2| flush aganst the back plate 22 and end plate 24. The endplate 23 is then moved toward the plate 24 until the edges of the sheetsin a face of the stack are firmly pressed thereagainst. If the sheets inthe stack are firmly stuck together or blocked, it is preferably firstto knead or flex the stack across the straight edge 20 of the bed plate2|) so as to loosen up the stack.

In operating the apparatus, the valve H is opened and the gas currentcauses the comminuted material I in the vessel I! to be sucked throughthe pipe I8 and into the manifold M where it is dispersed in the gas.The gas containing the dispersed comminuted material passes from thenozzles |5|5 through the openings 26-26 against the edge 30 of the stackI9 of sheets, as shown in Fig. 3. The force of the current of gas causesthe individual sheets 3| of the stack l9 to separate and the gas passingbetween the sheets deposits the particles 32 of the comminuted materialon the surface of the sheets.

There is shown in Fig. 4 a modification of the apparatus of Fig. 1 inwhich there are provided means for forcing the stack I9 to assume theshape of a trapezoid so as to produce a progressive overlapping oroffset of the successive sheets at the end as shown. The end plates 23and 24 may be inclined at an angle, preferably less than with respect tothe bed plate 20 so that the edge 30 of the stack which is positioned inthe current of gas is overhanging as shown in Fig. 4 which facilitatesthe entrance of the gas between the sheet. As a result of this novelarrangement, the entrance of the gas between the continuous sheets isfacilitated.

Another way of facilitating the separation of the sheets is to providemeans to flex or corrugate the stack. For example, the bed plate 2| andthe top plate 25 may be provided with alternating ribs 33 which functionto flex the sheets one or more times, or corrugate the stack as shown inFig. 5. When the stack is thus flexed or corru gated, air spaces 34-34are formed between adjacent sheets at intervals in the stack where thesheet changes direction intermediate of opposing ribs as shown in thedrawing.

If the stacked sheet material is found to be dried out and brittle, thegas used for separating the sheets may advantageously consist of orcomprise a known softening agent of the material and such treatment maybe made simultaneously with or subsequent to the treatment with thecomminuted material. For example, a suitable water aspirator is attachedto the gas line l2 and there is formed in the manifold l4 a mixture ofair, water vapor and comminuted material of nonhygroscopic character.This mixture is suitable for separating and simultaneously resofteningbrittle sheets of regenerated cellulose. On the other hand, a mixture ofair and alcohol vapor may be used with suitable comminuted material forseparating and softening sheets of cellulose acetate.

For the compressed gas cylinder I there may be substituted an aircompressor with a suitable motor to operate the same in a known manner.The gas pressure required to provide a suitable current will vary withthe sheet material and the condition of the stack at the time-oftreatment. In the appended claims, the expression gas curren is intendedto cover a current of suflicient volume and force to cause a separationof the sheets in the stack being treated.

The stack may be slightly inclined from the horizontal or positionedsubstantially vertically in the supporting means and the lower edges ofthe sheets subjected to the blast of gas containing comminuted materialby a suitable apparatus embodying the features of the invention. Whendisposed in this manner, the effect of gravity is partly overcome andthe separation of the sheets facilitated. To further facilitate theseparation of the sheets, the end plate 24 may be cut out at a pointintermediate its ends so that the edges of the sheets in the stack maybe riflied by hand while the gas current is played against the edges ofthe sheets. If desired, the end plate 23 may be suitably perforated toallow ready passage of the gas through the stack or the openings 2626may be placed in the back plate 22, particularly when the stack is to bepositioned substantially vertically.

The product treated with the apparatus of the invention is notmaterially altered in its general appearance. When a transparentmaterial is treated with particles of a size corresponding to 100 meshor above, the deposit of comminuted material is practically invisible,the transparency and lustre of the sheet being substantially unimpaired.The sheets in the treated stack are free-flowing and may beseparatedeasily by hand or automatic devices.

It appears probable that the various novel characteristics exhibited bythe treated material may be ascribed in part to the presence of theparticles anchored on the surface, and in part to the pockets of airprovided by them, which latter decrease the adherence by preventing thedirect contact of large smooth surface areas.

Since certain changes may be made in the above construction anddifferent embodiments of the invention could be made without departingfrom the scope thereof, it is intended that all matter contained in theabove description or shown in the accompanying drawing shall beinterpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. In an apparatus for treating a stack of sheet materials to render theindividual sheets separable, the combination of means to produce acurrent of a gas, means to disperse a comminuted material in saidcurrent and means to position a stack of sheets edgewise in said currentso that an edge-face is disposed at an oblique angle to the direction offlow of the gas thereagainst.

2. In an apparatus for treating a stack of sheet materials to render theindividual sheets separable, the combination of means to produce acurrent of a gas, means to disperse a comminuted material in saidcurrent, and means to position a stack of sheets edgewise in saidcurrent with the sheet edges progressively offset so that the comminutedmaterial will be inserted" between th sheets.

3. In an apparatus for treating a stack of sheet materials to render theindividual sheets separable, the combination of means to produce acurrent of a gas, means to disperse a comminuted material in saidcurrent and means to position a stack of sheets edgewise in said currentwith the sheet edges progressively offset comprising obliquelypositioned plates to engage the sheet edges on opposite sides of thestack.

4. In an apparatus for treating a stack of sheet materials to render theindividual sheets separable, the combination of means to produce acurrent of a gas, means to disperse a comminuted material in saidcurrent and means to position a stack of sheets edgewise in said currentcomprising a plate to engage a surface face, edge-face confining platesand a confining plate to engage the other surface face, the surface faceengaging plates having alternating ribs thereon for corrugating a stackof sheets confined therebetween.

5. An apparatus for treating a stack of sheets to render the individualsheets separable, comprising means to support the stack of sheets andrestrain movement thereof parallel to the plane of the sheets in a givendirection, means positioned to direct a current of gas substantially insaid given direction against the edges of the sheets in the stack, meansfor supplying a current of gas to said directing means, and means todisperse a comminuted material in said gas current whereby thecomminuted material will be inserted between the sheets.

6. An apparatus for treating a stack of sheets to render the individualsheets separable, comprising means to support the stack of sheets andrestrain movement thereof parallel to the plane of the sheets in a givendirection, means positioned to direct a current of gas substantially insaid given direction against the edges of the sheets in the stack, meansfor supplying a current of gas to said directing means, means todisperse a sheet softening agent in said gas current and means todisperse a comminuted material in said gas current whereby thecomminuted material will be inserted between the sheets.

ANDRE WALLACH.

